The present invention relates to a method and apparatus for examination of the visual acuity of a patient.
Examination of visual acuity represents one of the most important tests in ophthalmology. This test is utilized to provide the doctor with information on the existence on eye disease or abnormalities and provides an evaluation of treatment efficiency. Visual abilities include normal vision characteristics which are represented by the conventional 20/20 score of an individual who can read letters at twenty feet designed to be read at that distance. Accurate acuity measurements are required for vision evaluations or for scientific study where the results are reproducible. The required physiological conditions for visual acuity examinations are designated by the Concilium Ophthalmologicum Universale Budapest 1972 and in the recommendations by the National Eye Institute of Bethesda.
Known is an eye chart which is hung on a wall for testing visual acuity. Also known is a projector which projects a series of eye charts onto a screen. These projectors are commonly used by optometrists and opthamologists because they can conveniently display a number of charts. One main disadvantage of these projectors is the need for a darkened room in order to provide good contrast.